{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-90104", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-11T19:38:34.786Z", "datePublished": "2026-09-17T16:06:14.191Z", "dateUpdated": "2026-10-19T08:58:02.264Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:58:02.264Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nNFSv4.1: zero referring call lists before decoding\n\ndecode_cb_sequence_args() allocates csa_rclists with kmalloc_objs(), so\neach referring_call_list starts uninitialized. decode_rc_list() assigns\nrcl_refcalls only when rcl_nrefcalls is nonzero. A valid list with zero\nreferring calls therefore leaves the pointer uninitialized, and\nnfs4_callback_sequence() later passes stale slab contents to kfree().\n\nAllocate csa_rclists with kzalloc_objs() so every rcl_refcalls member is\nNULL from the beginning, including valid empty referring call lists." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - xs_read_stream_call()/rpcrdma_bc_receive_call() deliver a backchannel RPC_CALL on the established NFSv4.1 TCP or RPC/RDMA session into nfs4_callback_compound → process_op → decode_cb_sequence_args(); the attacker-controlled bytes are the CB_SEQUENCE csa_nrclists and rcl_nrefcalls XDR fields sent by the NFS server.\nAC:L - A single well-formed CB_SEQUENCE with csa_nrclists≥1 and decode_rc_list() seeing rcl_nrefcalls==0 skips the rcl_refcalls assignment and still returns 0; nfs4_callback_sequence() then kfree()s that stale pointer. Empty referring_call_list4 is valid RFC 5661 XDR, so no race or victim-only state is required.\nPR:N - nfs_callback_authenticate() accepts RPC_AUTH_UNIX on the NFSv4.1 backchannel, and decode_cb_sequence_args() runs in process_op() before nfs4_find_client_sessionid(); the connected NFS server needs no account or capability on the client to send CB_SEQUENCE.\nUI:N - After nfs4_init_callback() has attached the backchannel (boot-time, autofs, or Kubernetes NFSv4.1 mounts), the server unilaterally sends CB_SEQUENCE; nfs4_callback_sequence() kfree()s rcl_refcalls with no further victim open, mount, or click.\nS:U - kfree of the stale rcl_refcalls pointer corrupts the NFS client's kmalloc heap in the same host kernel; it does not cross a VM, IOMMU, or guest/host boundary.\nC:H - nfs4_callback_sequence() kfree()s uninitialized rcl_refcalls left by kmalloc_objs() of csa_rclists when rcl_nrefcalls was 0. A prior CB_SEQUENCE that allocated then freed rcl_refcalls can leave that pointer in the reused slab object, a heap double-free/UAF read primitive.\nI:H - The same kfree of stale rcl_refcalls is a slab double-free of the referring_call array (size chosen by the attacker's earlier nrefcalls). Reclaim or spraying a replacement object over that free yields an arbitrary kernel write / control-flow hijack primitive.\nA:H - kfree of a non-NULL garbage rcl_refcalls pointer from a successful decode_cb_sequence_args() of an empty referring_call_list causes SLUB to BUG, oops, or panic even when the double-free is not fully exploited." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfs/callback_xdr.c" ], "versions": [ { "version": "4aece6a19cf7f474f15eb861ba74db4479884ce3", "lessThan": "f4d23937e1c41995c2f54af26c89b5e48a41c299", "status": "affected", "versionType": "git" }, { "version": "4aece6a19cf7f474f15eb861ba74db4479884ce3", "lessThan": "f31f3c042e024aef437cda42f0424ae8d4594b6c", "status": "affected", "versionType": "git" }, { "version": "4aece6a19cf7f474f15eb861ba74db4479884ce3", "lessThan": "8fa4804fe62ca4155a2d8fc2789d630376cbf2fc", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "fs/nfs/callback_xdr.c" ], "versions": [ { "version": "2.6.31", "status": "affected" }, { "version": "0", "lessThan": "2.6.31", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.57", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.6", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.31", "versionEndExcluding": "6.18.57" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.31", "versionEndExcluding": "7.2.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.31", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/f4d23937e1c41995c2f54af26c89b5e48a41c299" }, { "url": "https://git.kernel.org/stable/c/f31f3c042e024aef437cda42f0424ae8d4594b6c" }, { "url": "https://git.kernel.org/stable/c/8fa4804fe62ca4155a2d8fc2789d630376cbf2fc" } ], "title": "NFSv4.1: zero referring call lists before decoding", "x_generator": { "engine": "bippy-1.2.0" } } } }